Optometer.



Patented Sept?. I8, |900.

A. J1.y CRUSS` UPTUMETER.,

(Application filed Jung-16, 1899.)

(No Modal.)

W/TNESSES /NVENTUH wa/wu/ y GMA.

A 7TOHNEYS ma Norms varen; co mow-mum WASHINGTON. u. c.

UNTTED STATES ANDREW JAY CROSS,

PATENT OFFICE.

'oE NEW YORK, N. Y.

oPToMETER.

SPECIFICATION forming part of Letters Patent No. 657,919, datedSeptember 18, 1900.

Application filed June 16, 1899.

of measuring the refractive condition of eyes in an objective manner isaccomplished by means of reflected light, the mirrors used for thispurpose being both plane and curved with a perforation in the center andknown by the technical terms opthalmascope, retinoscope, skiascope,dac., the most popular instruments for this purpose being the lattertwo. The method is also known by several names those of retinoscopy,skiascopy, and shadow-test being generally employed. Considerable skillis required in making tests by this method, owing to the smallness ofthe pupil ofthe eye under examination; also, to the multiplicity ofextraneous light reflections caused by the mirror-like surface of thelenses when they are placed before an eye. Then, too, much trouble isexperienced by the examiner in changing all these lenses in order thatthe light may be properly refracted. My invention is designed toovercome these drawbacks and to greatly increase the apparent size ofthe pupil, obviate the extraneous light reflections, and enable theexaminer to control the refractive value of the instrument or lensseries by means of cords or equivalent devices instead of by placing andreplacing lenses of varying strength.

Another object of my invention is to mechanically arrange the lensseries forming its essential feature, so that the same may be veryconveniently operated in any necessary combination or inclination to getthe right refractive effect.

'Io these ends my invention consists of an eye-testing apparatus theconstruction and arrangement of which will be hereinafter described andclaimed.

Serial No. 720,765. lNo model.)

In the drawings, wherein similar characters 2 of reference designatesimilar parts, Figure ,l

Ving my invention. Fig. 2 is a broken vertical cross-section on the lineII Il of Fig. 3, showing a detail of the sight-tubes and the graduatedarc surrounding the tubes. F ig.

III III of Fig. 2. Fig. 4 is a broken inverted tubes.- Fig. 5 is adetail section of the handle and its connection with thesupportinginverted plan view, partly in section, of the overlapping armsand handle which carry the sight-tubes.

In this invention two sight-tubes 10 are emrear end, being cutaway atthe top, as shown at 1l, so that the examiner can get better light andmore conveniently look through them into the eyes of the patient.Obviously better to have two, and these carry the sev eral lenses to bepresently described and are held parallel with each other on a suitablehandle, so that the subject whose eyes-are to as he would a long-handledopera-glass while the examiner looks through the instrument and into thepupil of the patients'eye.

In each tube is a series of lenses A and A' and are placed 'ith theiraxes at slight angles to the perpendicular.' The lenses A and A havetheir axes horizontal7 and they are also in harmony as to angle, whilethe lenses B having Vertical axes and similar angles. The lenses Aand Bare negative lenses and are given the right inclination to each other,and they are also held in a stationary position,

and are slidable longitudinally in relation to each other and inrelation to the fixed lenses A and B. It will be seen that thisarrangement of lenses placed at correct angles to of them movable, so asto get the right eect of magnification, gives the following results:First, it enables the apparent size of the pupil to be quicklyincreased, so it can be seen is aperspective view of the apparatusembody 5 5 3 is a broken longitudinal section on the line 6o plan,partly in section7 of one of the sightm arms of the sight-tubes; andFig. 6 is a broken 65 ployed, which are preferably inclined at the 7oone tube can be used, if preferred; but it is f be examined holds theinstrument to his eyes 8o andB and B. These lenses are all cylinders andB are likewise similarl in harmon o while the lenses A and B arepositive lenses have the right refractive effect and withl part Ioodistinctly at a distance of one or more meters, second, it overcomesextraneous light reflections Without interfering With the refractivevalve of the lenses used, and, third, it enables the examiner to controlthe spherical and cylindrical lens quantity desired. The mechanism bywhich all this is accomplished will be now described.

.The several lenses are mounted in the customary lens-rings 12, in whichthey are held by the split rings 13; but it will of course be understoodthat the lenses may be mounted 'lenses described, detrimental reflectiveand shadow effects. The lenses A and B have their rings fixed toslide-blocks 15, which are movable back and forth in the tube, extendingdownward through an opening 16 in the tube-bottom, and the said blocksare widened at their lower ends and have upturned flanges 17, so as togive them a better grip on the guide-rods 18, on which they slide. Thiswidening of the slide-blocks causes the lensrings to be held steadily,which is of course necessary. It will be noticed that theselastmentioned lenses A and B' are inclined also laterally andvertically, and as their meridional axes are at right angles to eachother they have when in close connection a spherical effect, and whenseparated more or less spherical or cylindrical effects can be had whentaken in connection with the other lenses A and B,which are alsocylinders having meridional axes at right angles to each other.

The guide-rods 18 can be held in any convenient way; but, as shown, theyare at one end fixed in a hanger 19, depending from the rear end of thetube 10,. and at the other in the ring 20, which encircles the tube andis fixed to the same. In this connection it will be noticed, especiallyby reference to Fig. 2, that the ring 20 has a graduated scale thereonadapted to turn with the tube opposite the vertical mark 21 on the fixedportion 36 of the apparatus,hereinafte r to be described, so that theaxis of cylindrical curvature can be noticed by reference to the markand the scale. It is of course apparent that the marked part can be madeto move with the tube and the scale held stationary with the saine eect.

To provide for moving the slide-blocks 15 separately or in unison, oneof them is provided with a latch 22, which is pivoted on its under side,as shown at 23, and has its movement limited by the studs 24, which arefixed to the block, and this latch overlaps the other slide-block 15 andhas its ends formed into eyes 25 to receive the cord by which it isoperated. The locking end of the latch is provided with a shoulder 26,which is adapted to engage a stud 27 on the second block 15. The latchis operated and the slide-blocks and their lenses moved by a cord 28,one end 29 of which is fixed to the rear eye 25 of the latch and theother end 30 of which is passed around a pulley 31 and secured totheforward eye 25 of the latch. The pulley 31 is pivoted in a suitablehanger 32 at the front end of the tube for the purpose of giving theright direction to the latch and slide-blocks when the cord 28 ispulled.

Referring now especially to Fig. 4, it will be seen that by pulling onthel end 29 of the cord and at the same time bearing slightly to oneside the latch can be held in connection With the stud 27, so that bothslide-blocks 15 are locked together and the two lenses A and B aresimultaneously moved, and moved to the same extent, so that the desiredmagnifying spherical effect can be obtained; but if the slide-blocks 15are to be moved separately the operator carries the end 29 of the cordin the opposite direction, which turns the latch 22 on its pivot andreleases it from the stud 27, thus unlocking the slide-blocks, and sothe continued movement of the end 29 of the cord will pull forward therear slideblock 15 and lens B without in the least affecting the otherslide-block and the lens A'. By pulling on the end 30 of the cord therear slide-block 15 can be pulled back until it is in connection orabutment with the forward slide-block 15, after which both slide-blocksand their lenses may be moved forward by a continued pull in the samedirection. It will thus be seen that the examiner can stand therequisite distance in front of the apparatus i and look through it intothe pupils of his patients eyes and that by a very slight manipulationof the cord 2S he can place the movable lenses A and B into position toget whatever effect is necessary.

In order that the position of the lenses may be correctly noted lwhenthey are placed in position to get the desired effect, a graduated tableC is produced on the side of the tube, and indicators or pointers 33 and34 are attached to the slide-blocks 15 of the lenses A and B', so as tomove along this table. The tube at its front end is journaled in asupporting-ring 35 and held in position by a nut 35a, which is screwedto the exterior of the tube at the front end. This ring 35 has anextension 36 at the top, on which is produced the indicating-mark 21,above noted, and the extension carries the angle-bracket 37, to which ispivoted the second angle-bracket 38, and this carries the headpiece 39,adapted to rest against the brow of the patient. This arrangement of theheadpiece is not specifically described or claimed, because it is shownand described in another applica- TOO IIO

tion, Serial No. 720,764, for an eye-measuring instrument which I havefiled simultaneously with this one. The ring 35 has also an arm 40 onits under side, to which is held the stem 4l of the clip 42, which isnot described in detail, because it is like the usual clips for thispurpose and is held in front of the sight-tube to receive anyauxiliarylenses which may be necessary in examining the eyes. The parts40 and 4l are secured by a screw 43 or similar fastening to the upturnedend 44 of the horizontal arm 45 46, which extends backward and laterallybeneath the sight-tube, where it overlaps a similar arm of the secondsight-tube, the lower arm being slotted at 46a and the upper beingprovided with a nut 47, adapted to receive the screw-threaded end 48(see Fig. 5) of the handle 49. This arrangement provides for the easylateral adjustment of the tubes and the support of them; but in detailit is described and claimed in my other application above referred to.

From the foregoing description it will be noted that the subject orpatient can place the apparatus to his eyes, that the examiner may thenstand in front of him the correct distance and by manipulating the cords28 can easily bring the lenses to the desired position, so that thepupil of the eye may be made the right apparent size and quickly viewed.

I have referred heretofore to the essential facts relating to thesuccessful examination of the eyethat is, theinstrument must increasethe apparent size of the pupil, so that it can be seen distinctly at adistance of one or more meters away; second, it must overcome extraneouslight reflection without interfering with the refractive value of thelenses used, and, third, that it must enable the sphericalandcylindrical lens quantity to be easilycontrolled. That these points arefully covered in the invention herein described will be seen from theforegoing description, in connection with the following statement:vWith-reference to the first essential it must be borne in mind that thereason the shadow reverses, in estimating refractive errors byskiametry, is due to the fact that the emerging rays of light from aneye undergoing examination cross one another in front of both patientand examiner. The rays therefore in order to show a pronounced movementone way or the other in the form of light or shadows must be interceptedby the examiners eye at a point considerably removed from the place where the rays cross. If, say, a two-diopter convex lens is used where/theillumination is from parallel rays of light, this crossing in raysemerging from an emmetropic eye will be at a distance of twenty inches.Add a quarter of a diopter,

and the crossing will take place at eighteen inches distance; subtract aquarter, and the crossing will be at twenty-two inches, or a variationof only about two inches either way. ow if a lens of three-quarters ofai diopter is employed the crossing. of the rays will be at aboutfifty-three inches distance; u

add a quarter of a diopter, and the crossing will be changed to fortyinches; subtract a quarter, and it will be at eighty inches, a variationof thirteen inches one way and of twenty-seven inches the other. Hencethe value of the weaker lens-power from a skiametrical point of view.The greater the increase in distance between patient and examiner,however, the more difficult it becomes for ihe latter to see the pupilof the former, and it is for this reason that the size of many pupilsmust be magnified or apparently enlarged. As to the second essential,wherein extraneous light reflections are to be overcome withoutinterference with the refractive value of the lenses, it is well knownthat the slightest tilting of a spherical lens or the transmitting ofrays of light through it in any direction other than that which is inaccord with its optical axis will cause appreciable spherial errors, orwhat is called cylindrical equivalents. This law applies to cylindricallenses, too, in all but one meridian, and that one is its axis, so thatif the tilting of the lens is parallel to this axis the-only error thatwill manifest itself will be of a slightly-prismatic nature, producing acurved displacement. Now as to the third essential, regarding the easyand practical manner of controlling the lens-powerfrom adistance, itwill be seen that it is quite necessary for the examiner to remain at afixed distance from the patient, so as to be able to note any slightvariation in lens-power without having to alter this position in orderto change lenses. Then, too, speed is a consideration, for nearly allobjective examinations are more or less fatiguing and uninteresting topatients in general. The examiner, therefore, when one hand is occupiedwith the skiascope-mirror, should be able to fully govern ihe lens-powerof the retinoskiameter with the other hand, and at any distance forwhich the instrument may be adjusted.

It will be noticed that the essential thing in this invention is to havethe series of cylindrical lenses arranged in pairs, as stated, withtheir meridional axes at right angles to each other, that the planes ofthe positive and negative lenses should be parallel, and that eachcorrelated pair be inclined to the necessary extent from theperpendicular, and it will be further noticed thatthis effect can be hadand that the necessary movements may be given with mechanism differinggreatly from that herein illustrated and described. Consequently I donot confine the invention to the precise form of apparatus hereindisclosed.

Having thus described my invention, I claim as new and desire to secureby Letters Patent l. The combination of a series of cylindrical lensesarranged on a common optical axis and inclined in relation to eachother.

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2. The combination of a series of cylindrical lenses arranged on acommon optical axis, said lenses being inclined and movable along theiroptical axis in relation to each other.

3. An apparatus of the kind described comprising a rotatably-mountedsight-tube and cylindrical lenses arranged therein, the lenses beinginclined with relation to each other, substantially as described.

4. A-n apparatus ofthe kind described, comated.

5. In an apparatus of the kind described,

the combination of the cylindrical lenses with crossing meridional axesto produce spherical effects, the lenses being inclined in relation toeach other, substantially as described.

' 6. In an apparatus of the kind described, the combination of a seriesof cylindrical lenses arranged on a common optical axis with crossingmeridional faxes, the lenses being inclined'iireiation "toM each-otherand some of them being movable With respect-tok the others.

7. Thecombination of the series of cylindrical lenses arranged on acommon optical axis and inclined in relation to each other, some of thelenses being movable along their optical axis in relation to the otherlenses, and means for operating the said lenses, said means beingextensible from the instrument in which the lenses are supported.

8. An apparatus of the kind described comprising a series of correlatedpairs of cylindrical lenses, one pair being stationary and the othersmovable in respect to the stationary lenses and in relation to eachother.

9. An apparatus of the kind described comprising a series of cylindricallenses arranged in correlated pairs, one pair being stationary and theother lenses movable in relation to the stationary lenses and to eachother, the several lenses being also inclined in relation to each other.

l0. The combination with the stationary lenses of the movable lenses, alocking device to hold the movable lenses together, and mechanism formoving the movable lenses together or separately, substantially asdescribed.

11. The combination With the stationary lenses of the movable lenses, anoperatingcord to move the lenses, and a connection between the cord andlenses by means of which the latter may be moved together or separately,substantially as described.

12. An apparatus of the kind described comprising suitably supportedstationary lenses, a pair of movable lenses arranged on the same opticalaxis as the stationary lenses, 6 5

slide-blocks suitably supported carrying the movable lenses, a cord formoving the slideblocks, and a locking device operated by the cord tohold the slide-blocks together and to release the same, substantially asdescribed.

13. An apparatus of the kind described comprising a sight-tube, suitablestationary lenses therein, slidable lenses also mounted in the tube, alatch to hold the slidable lenses i together, and a cord connecting Withthe latch prising a series of cylindrical lenses arranged on a commonoptical axis, along which they are movable and inclined in relation toeach other, and means extensible from the support of the said lenses bywhich they can be operto operate the same and move the lenses,substantially as described.

14. An apparatus of the kind described comprising a sight-tube, a pairof stationary cylindrical lenses mounted therein,said lenses being atangles to each other and having their meridional axes at right angles,and a second pair of lenses movably mounted in the said tube, the saidsecond pair of lenses being also at angles to each other andhavingcrossing meridional axes, substantially as described.

15. In an apparatus of the kind described, the combination with thesight-tube and the stationary inclined cylindrical lenses therein havingcrossing meridional axes, of a second `pair of lenses mounted in thetube and movable longitudinally therein and in relation to each other,the movable lenses having axes, anglesand inclinations corresponding tothose of the stationary lenses, substantially as described.

16. In an apparatus of the kind described, l

the combination with-*the sight-tube of the stationary lenses therein,and the ring supporting the lenses, said "ring having diverging partsserving as abutments to the lensrings, substantially as described.

17. The combination With the sight-tube of the movable lenses therein,the slide-blocks carrying the lenses, and the latch pivoted on oneslide-block and means on the second slideblock for engagement with thelatch, substantially as described. S

18. The combination with the sight-tube having an opening therein, ofthe lens-rings protruding through the opening and\rneiging in theslide-blocks, the guide-rods supporting the slide-blocks, and the latchpivoted on one slide-block and engaging the other, substantially asdescribed.

19. The combination with the sight-tube, the movable lenses, and theslide-blocks carrying the lenses, of the latch pivotedJon oneslide-block and engaging the second. slideblock, a pulley in advance ofthe second slideblock, and a cord extending over the pulley, the ends ofthe cord being ixed to opposite ends of the latch, substantially asdescribed.

ANDREW JAY cncss.

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